Method of applying adhesive coated film

ABSTRACT

An adhesive-applying method is disclosed herein. The method comprises: providing a film comprising pressure sensitive adhesive coated on a major surface thereof; heating the film to a softening point of the film; and pressing the film against a substrate with an application device, the application device comprising a film-contacting portion, the film-contacting portion comprising a foam material and having a thermal conductivity of less than 1.8 BTU/hr-in-ft 2 -° F.; wherein the pressure sensitive adhesive on the major surface of the film adheres to the substrate. Application devices and kits that may be used in conjunction with the method are also disclosed herein.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/073,135, filed Nov. 6, 2013, which is a continuation of Ser. No.11/427,983, filed Jun. 30, 2006, now U.S. Pat. No. 8,608,897, which is acontinuation of U.S. application Ser. No. 09/479,648, filed Jan. 7,2000, now abandoned, which is a continuation-in-part of U.S. applicationSer. No. 09/236,806, filed Jan. 25, 1999, now abandoned, withdisclosures of which are incorporated herein by reference.

FIELD OF INVENTION

This invention concerns articles and methods to save labor effort andimprove quality of application in adhering adhesive-coated films tosurfaces of substrates, especially those having irregular surfaces.

BACKGROUND

Today, adhesive-coated plastic films, especially vinyl films withpressure sensitive adhesives or pressure-activated adhesives, areapplied to a variety of surfaces for a variety of reasons such asadvertisement, decoration, protection, and the like. Many of thosesurfaces contain rivets and other protrusions or indentations, such asthe side of a truck trailer. When the film is applied over and adheredto these irregular surfaces, the film is strained to bring the adhesiveinto contact with the irregular surface. Residual stress in the film atsuch irregular surface locations often exceeds the holding power of theadhesive resulting in the film lifting off the surface to which it wasadhered, particularly where the surface is irregular such as around arivet or rib reinforcing the side of a truck trailer.

Current techniques for application to irregular surfaces involveapplying most of the film with a small, plastic squeegee leaving a smallarea around the protrusion or indentation. Completing the applicationinvolves treating rivets to minimize lifting by heating the film with aheat source, usually a hot air gun or a torch, after the film has beenpredominately adhered to the irregular substrate. The film is typicallyheated while it is bridging the area around each type of surfaceirregularity, which can be summarized to be either a protrusion or anindentation. The film is not touched with the current tools because itis very soft and somewhat sticky. If it is touched, it is usuallydamaged. Because of the low mass of the film and the high temperature ofthe heat source, heating rates are several hundred degrees Celsius persecond. Similar cooling rates are also occurring. When the film is thenpushed into place with a tool, typically a squeegee for a rib or a rivetbrush for a rivet, it is only slightly above room temperature. This doesoffer and improvement over pressing the film without warming because thedelayed crystallization time of the film makes the film more compliant.A rivet brush is usually a stiff brush, usually about 2.54 cm indiameter with 1.25 cm long bristles attached to a short wooden handle.If the film is too soft because of the heating when it is contacted witha circular motion using the rivet brush, the film is likely to bedamaged. If the film is too cool, the stress is not eliminatedadequately, lifting results eventually. In an attempt to relax theresidual stress, the film is often heated after application, but thetemperature to which the film can be raised is limited by the thermalconductivity of the metal surfaces underneath the film. It is thereforevery difficult for one skilled in the art to assuredly adhere theadhesive-coated film to the irregular surface while the film is fullysoftened without also damaging the film structure or its appearance. Ifthere is damage, the film is weakened at that location and diminishesthe durability of the film. If there is an image graphic on that film,the image is distorted or destroyed at the damaged location. Anaberration in an image, even if the image is as large as a mural on theside of truck trailer, is quite noticeable and unsatisfactory to theowner of the trailer, the marketer of a product shown in the mural onthe trailer, and the graphic fabricator who has invested considerablelabor and other effort to adhere the graphic film to the side of thetrailer.

If the film lifts because of residual stress, the film could crack, peelback, or be damaged and otherwise not meet expectations for a surfacethat should have paint-like appearance.

SUMMARY

An adhesive-applying method is disclosed herein. The method comprises:providing a film comprising pressure sensitive adhesive coated on amajor surface thereof; heating the film to a softening point of thefilm; and pressing the film against a substrate with an applicationdevice, the application device comprising a film-contacting portion, thefilm-contacting portion comprising a foam material and having a thermalconductivity of less than 1.8 BTU/hr-in-ft²-° F.; wherein the pressuresensitive adhesive on the major surface of the film adheres to thesubstrate. Application devices and kits that may be used in conjunctionwith the method are also disclosed herein.

A labor-saving method for adhering an adhesive-coated film to asubstrate having a surface is also disclosed herein. The labor-savingmethod comprises: distributing the film described above to a party thathas been taught to use the adhesive-applying method of described above;optionally permitting the party to print an image on the film; andpermitting the party to use the adhesive-applying method of describedabove.

The methods, application devices, and kits disclosed herein may be usedwith little training so that less skilled employees and consumers canobtain properly adhered films on substrates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates application of a film to a substrate according usingan exemplary application device.

FIG. 2 is a perspective view of a second embodiment of the article ofthe present invention.

FIG. 3 is a perspective view of a third embodiment of the article of thepresent invention.

FIG. 4 is an illustration of another embodiment of the article of thepresent invention.

FIG. 5 is an illustration of another embodiment of the article of thepresent invention.

DETAILED DESCRIPTION

The application devices, methods and kits have been described in U.S.application Ser. No. 09/479,648, filed Jan. 7, 2000, the disclosure ofwhich is incorporated by reference for all that it contains.

Adhesion of adhesive-coated plastic films, particularly vinyl films,applied to flat and irregular surfaces is problematic with respect toappearance, durability, etc. As used herein, an “irregular surface” is ahighly textured surface that does not allow complete conformance of anadhesive coated film to its surface due to the presence of protrusions,indentations or other such non-planar geometries. For example, anirregular surface may be sufficiently non-uniform such that a 4 mil filmwhen applied thereto with a 4 kg rolling weight, makes contact with thesurface at less than 90% of its surface area.

Because a film is usually stretched during application, especially toaccommodate an irregular surface, the pressure sensitive adhesive musthold the film to the surface under various stresses. Previously, onlyfilms with high performance adhesives have been used in such anapplication with success. Some of the most common challenging surfacesinclude corrugated and riveted truck sides, curved vehicle panels,channels in containers and vehicles, etc.

Surprisingly, excellent adhesion of thermoplastic films to highlyirregular or textured surfaces, such as concrete, cement block, stucco,brick, fabric surfaces, carpeted surfaces and the like, may be obtainedwith the adhesive-applying method described herein. Films applied tosuch surfaces without the adhesive-applying method described herein havesignificant portions that are not in contact with the surface of thesubstrate, particularly on the edges of the film. Films applied to suchsurfaces using the adhesive-applying method described herein have theappearance of being painted on the surface, due to the close conformanceof the film to the substrate. Further, the edges of the film areadvantageously in close conformance to the substrate, thereby reducingthe temptation of passersby to peel away the film.

As will be readily understood by anyone who has attempted to hangwallpaper, the application of an adhesive-coated film to a verticalsurface is very cumbersome and time-consuming. Application of suchmaterials to challenging surfaces such as truck trailers is that muchmore difficult. At the least, the wall is usually even and does notcontain compound geometrical or irregular surfaces. Typically, the sizeof a wallpaper section is about 70 cm wide and about 2.5 m long. Theapplication of an adhesive-coated film to a vertical side of a trucktrailer occurs in a vastly different environment: a substrate that isoften filled with topographical irregularities and film sections havinga size of about 120 cm wide and about 3 m long. Very skilled persons areneeded for this assembly, and such assembly takes very long times: onthe order of 22 hours per truck trailer.

Typical methods require individual treatment of each rivet area,including first punching holes in the film to allow air to escape,applying heat to the film to somewhat soften the film, and finallyapplying pressure using a brush to press the film down on the substrateusing a circular motion and firm pressure. Because of the pressure andmotion required in this application, the film could not be very soft atthe time of brushing the film into place. The film had to be allowed tocool to a temperature at which the structural integrity of the filmcould withstand the forces imparted on it by the brush. Damage to thefilm and/or poor placement of the film over the rivet areas oftenoccurred. In contrast, the adhesive-applying method disclosed hereinallows single stroke application of the film to the substrate on eachrivet without concern over tearing or otherwise damaging the filmthrough the swirling application of force through the rivet brush. Thisdifference in application technique may reduce application time ofapplying a film to a truck trailer related to finishing the rivets ofabout 50%.

The adhesive-applying method described herein may provide a laborsavings for the application of an image graphic film to a large verticalsubstrate having compound geometrical or irregular surfaces. As aresult, overall total cost may be substantially reduced. Even with thecost of film remaining constant, the labor savings reduces as much as 50percent total cost for the application of a non-printed film to acorrugated and riveted trailer.

The adhesive-applying method described herein makes it possible toadhere films to trailers and other challenging environment areas usingadhesives that are much less aggressive than was previously used. Thisis a significant advantage, because the end user may now more easilyremove the films with removal costs being substantially reduced, on theorder of 50%. Removable and/or repositionable adhesives may now muchmore readily be used.

It is virtually impossible to fully soften the film such that allresidual stresses are removed and still apply the film usingconventional tools without damaging the films. Furthermore, lack ofcontrol of the heating process and very rapid cooling of the film afterheating usually cause inconsistent results even with high performanceadhesives and skilled applicators.

The use of films with removable adhesives is very desirable in the shortterm advertising market, i.e., displays of less than about 12 months.Films having removable adhesives are predominantly used on flat surfacesbecause the adhesives do not adequately resist the residual stressremaining after application to non-flat surfaces using prior arttechniques. Much higher heat is required to fully relax the film thancan be applied using only the standard squeegee and rivet brush.

The adhesive-applying method disclosed herein provides for theapplication of heat and pressure at a location on a large flat surfaceduring adhesion in such a manner that minute stresses in a film beingadhered to the flat surface are removed prior to adhesion. Theadhesive-applying method disclosed herein also provides for theapplication of heat and pressure to a location of surface irregularityon the substrate in a time-space manner that provides thermal andmechanical alteration of the film at the location of surfaceirregularity or compound geometry and in a manner that the pressuresource is heat neutral.

The adhesive-applying method disclosed herein may be used for applyingan adhesive-coated film to a substrate, the adhesive-applying methodcomprising: providing a film comprising pressure sensitive adhesivecoated on a major surface thereof; heating the film to a softening pointof the film; and pressing the film against a substrate with anapplication device, the application device comprising a film-contactingportion, the film-contacting portion comprising a foam material andhaving a thermal conductivity of less than 1.8 BTU/hr-in-ft²-° F.;wherein the pressure sensitive adhesive on the major surface of the filmadheres to the substrate.

The adhesive-applying method disclosed herein employs an applicationdevice comprising a film-contacting portion, the film-contacting portioncomprising a foam material and having a thermal conductivity of lessthan 1.8 BTU/hr-in-ft²-° F. The application device may be described as apressure source. In general, the film-contacting portion has thermalconductivity characteristics and surface characteristics such that whenthe film is in contact therewith, it does not adhere thereto, even whenthe film is nearly melted.

With respect to the thermal conductivity characteristics, thefilm-contacting portion does not appreciably conduct heat either to orfrom the surface of the film as the film is applied under pressure to asurface on the substrate. In other words, the thermal conductivity ofthe film-contacting portion is low but can withstand high temperatures.Desirably, the thermal conductivity is less than 1.8 BTU/hr-in-ft²-° F.with thermal conductivity measured according to ASTM C-518.

The film-contacting portion comprises a foam material. The particularfoam material used may be determined quickly and routinely by applyingthe adhesive-coated film to the substrate, heating the non-contactingportion of the film to nearly its melting point, and then immediatelyusing the foam material to press the film to the substrate in anessentially perpendicular manner (without applying rotational force). Ifthe film sticks to the foam material or is damaged by the foam material,then it is not suitable for use. Thus, in general, the film-contactingportion has a low enough surface energy relative to that of the softenedfilm. Examples of suitable foam materials include materials known in thelow adhesion backsize art, such as open cell foam materials and foamedsilicone materials. Perfluorinated materials may also be used.

The foam material may be compressive to allow full contact of the filmwith the substrate, for example, in cases where the substrate has one ormore protruding rivets. In general, it is desirable for the film toconform around protrusions such that full conformation or compliance ofthe film around any surface irregularity of the substrate may beobtained depending on the intended application. Preferably, the foammaterial has a Poisson's ratio of less than 1, and more preferably lessthan 0.9. In some cases, it may be desirable for the foam material tohave a uniform surface structure such that when placed on a molten film,the film will not exhibit visible structure imprinted from the foammaterial. The application device may comprise a hand-held dauber typedevice that can provide a localized pressure around particularirregularities in the substrate surfaces. Preferably, the surface areaof the dauber is somewhat larger than the area of a rivet that wouldconventionally appear on a truck. For example, the application devicemay have a pressure-imparting surface of about 7 cm diameter.

The film-contacting portion may be in the form of a roller, much like apaint roller. The width of the roller depends on the application, forexample, for applying film to a corregated surface or a surface withrivets, a roller width of 2-15 cm is generally preferred. Theapplication device may be designed to impart essentially perpendicularforce with respect to the substrate with little or no transverse forceto the film during application.

In the adhesive-applying method described herein, the film to be appliedto the substrate is heated to a softening temperature of the film, suchthat the film is highly flexible and soft as compared to the film'sproperties at room temperature. The softening temperature of the filmmay be nearly the melting temperature of the film—just below thetemperature at which the film would discolor or develop holes.

The adhesive-applying method described herein comprises heating the filmto a softening point of the film. Heating may comprise heating the filmusing hot air, or by using infrared radiation. Heating may compriseheating the entire film or heating a selected portion of the film. Inaddition, heating may be carried out before or after the film is appliedto the substrate. In one example, the entire film could be heated andapplied at the same time. In another example, heating may be carried outwhile the film is in contact with the film-contacting portion beforepressing the film against the substrate: the film could be applied to anirregular surface without heating, maximizing the contact of the film tothe substrate, and leaving portions of the film not in contact with thesubstrate, but which are “tented” between adhesively contactingportions. Those portions of the film that are not in contact with thesubstrate are then heated to a softening point of the film, and appliedto the substrate by pressing. In this case, the application device wouldbe used to actually move the softened film into contact with thesubstrate. Surprisingly, the film fully conforms to the surface withoutdamage to the film.

The heat source and the film-contacting portion may be separate or thesame within the application device. For example, the method may comprisea two-person operation, wherein one person operates the heat source anda second person quickly follows with the film-contacting portion. Foranother example, one person may carry out the method by using ahand-held heat source (much like a hair dryer) in one hand, and a handheld film-contacting portion (much like a dauber) in the other hand. Themethod thus may proceed in a rhythmic motion of first applying heat withone hand, and immediately applying pressure with the other, down a rowof rivets or the like.

In the method of the present invention, it is often desirable to firstprovide air holes in the film immediately surrounding the surfaceirregularity at the portion where the film is not in contact with thesubstrate prior to heating the film. Such air holes provide an escaperoute for air that is trapped between the film and the substrate. Inmost cases, it is desirable for the film-contacting portion to allow airto escape during application of pressure to the film.

In some cases, it may be desirable for the film-contacting portion to besmooth enough so that markings are not imprinted onto the softened film.The foam material generally comprises cells, and in this case, the cellsmay need to be not so large as to imprint the cell pattern onto thesoftened film. The cells may be no larger than about 0.5 mm in diameter,for example, no larger than 0.2 mm.

Any adhesive-coated film may be used. In general, the film comprises afilm having a pressure sensitive adhesive coated on a major surfacethereof. The pressure sensitive adhesive may or may not be aheat-activated adhesive. The pressure sensitive adhesive may also be aremovable and/or repositionable adhesive, for example, Scotchcal™ Series3500 films available from 3M Company. As used herein, an adhesive isconsidered to be “removable” if, upon application to an intendedsubstrate the product ca be removed without damage to the substrate atthe end of its intended life at a rate in excess of 25 feet/hour (7.62meters/hour) by hand with the optional use of heat.

The film may comprise any of a variety of films including elastic filmsthat normally would be unsuitable for graphic applications, especiallyon irregular surfaces. Such films would ordinarily exhibit significantmemory upon application to uneven substrates, however, with the methoddisclosed herein, they can be thermally relaxed during application toremove residual stress. Useful films include vinyl films, polyolefinfilms, unoriented polyolefin films, polyurethane films, ionomeric resinfilms, acrylic films, fluoroelastomeric films, and the like.

Further, the film may be a rigid film that exhibits good handleabilityand durability, because such films are now capable of being softened atthe time of application to conform to irregular or compound curvesurfaces. Examples of rigid films are poly(meth)acrylates films, rigidpolyvinyl chloride sheets, polyester films, oriented polyolefin films,polycarbonate sheets, styrene sheets, and the like.

A particular example of a useful film is presently sold by 3M Company ofSt. Paul, Minn., USA under the brands of Scotchcal™; Controltac™ and thelike. Examples using these films are described below.

Also disclosed herein is a kit for application of films to a substrate,the kit comprising: an application device comprising a film-contactingportion, the film-contacting portion comprising a foam material andhaving a thermal conductivity of less than 1.8 BTU/hr-in-ft²-° F.; and aheat source adapted for applying heat to an adhesive coated film duringapplication of the adhesive coated film to a substrate.

Also disclosed herein is a labor-saving method for adhering anadhesive-coated film to a substrate having a surface, the labor-savingmethod comprising: distributing the film described above to a party thathas been taught to use the adhesive-applying method described above;optionally permitting the party to print an image on the film; andpermitting the party to use the adhesive-applying method describedabove.

An entirely new business method can be created using the applicationdevices and methods described herein. The business method comprisescontracting with an owner of an image to make that image on a graphicmarking film, wherein the maker of the graphic marking film prints theimage and assembles the image graphic film onto a substrate using theapplication devices and methods disclosed herein. Alternatively, thefilm maker can subcontract the use of the application devices andmethods to permit remote subcontractor(s) to assemble the graphicfilm(s) on the substrate(s) for further distribution or usage. The imagemay be distributed to multiple remote locations and printed andassembled using the same techniques at all locations, all benefitingfrom the labor savings afforded by the application devices and methodsdescribed herein.

FIG. 1 illustrates application of a film to a substrate using anexemplary application device. Application device 10 contains a heatsource 12 and a pressure source 14 wherein the pressure source isconstructed of a heat neutral material. A film 30 is applied to asurface 40 of a substrate 50, having a location 52 where film 30 isadhered and a location 54 where film 30 has not yet been applied.Application device 10 moves in a direction 60. Heat source 12 can have anozzle 70 for directing heat toward the film 30 at the location 54before film 30 is contacted by pressure source 14 in the form of aroller that is constructed of a material that conforms to any surfaceirregularities or compound geometrical locations on surface 40 ofsubstrate 50. The film 30 at location 54 receives an intersection ofheat and pressure but not combined heat and pressure within the pressuresource 14. Thus, the film 30 is heated before contacting the surface 40,but any dissipation of heat occurs through the substrate 50 not thepressure source 14. In this manner, unexpectedly, the intersection ofheat and pressure for the film 30 does not harm the structure of thefilm 30 or mar its surface that can contain an image graphic.

FIG. 2 illustrates application of a film to a substrate using anexemplary application device. Application device 110 for a substrate(e.g., utility vehicle such as a truck trailer or delivery van) that bydesign has surface irregularities of rivets and/or curves atcorrugations, where the application device 110 has a heat source 112 anda surface-conforming pressure source 114 connected by a frame 116 with afirst handle 118. Optionally, but preferably, the application device 110also has a second handle 120 for guiding the application device 110, atemperature sensor 122 for measuring the temperature of the heat source112, a temperature controller 124 for controlling and optionallydisplaying the temperature measured by the sensor 122. The frame 116should provide sturdy but lightweight support for the other elements ofthe application device 110 and can be constructed from materials such aslightweight metal or rigid polymer.

The heat source 112 can be any heat source that is capable of generatingtemperatures such that the film is maintained at a softening point forthe film until pressed against the irregular or compound surface by thepressure source 114. At that temperature, the film is softened andexhibits little or no tendency to recover making the film conformablefor adhesion to the irregular surface or compound surface. Preferably,the temperature ranges from about 150° C. to about 350° C., depending onthe composition of the film to be softened. Nonlimiting examples of suchheat sources include heat guns generating hot air; quartz heatersgenerating infrared radiation; propane; and the like. The power for suchheat source 112 can be connected to the frame 116 or remote from theframe 116, either an electrical or fuel heat element with a fan orcompressed air source. Preferably, the heat source 112 is an electricalheating element of at least 300 Watts of power with a temperature sensor122 and temperature controller 124. As seen in FIG. 2, a source of airto be heated by heat source 112 can be a remote air blower 125 connectedto frame 116.

Application device 110 has a pressure source 114 that has a compliantsurface that has low thermal conductivity. Generally, the pressuresource 114 is a surface used to press the film into position, shouldmatch the irregularity of the substrate surface, and should retain theheat from heat source 112 until the film is brought into contact withthe substrate surface. In the embodiment of FIG. 2, a roller 114 is usedthat rotates on an axle 126 mounted on the frame 116. Nonlimitingexamples that have both a compliant surface and low thermal conductivityinclude natural or synthetic rubber; urethane polymers; siliconepolymers (such as Rogers 800 Poron™ silicone foam, ½ inch thick);fluoroelastomers; and especially foamed version of those materials; andthe like.

The use of application device 110 is enhanced from the positioning of asecond handle 120 on the frame 116 along an axis near the point wherethe heat source 112 and pressure source 114 intersect on the filmadhered to the substrate. This forward position for second handle 120,along with first handle 118 trailing the point where the heat source 112and the pressure source 114 intersect, create an axis X-X of applicationfor application device 110 along the substrate. This axis X-X helps aperson guide the application device 110 for labor-saving, single-passuse of the application device 110.

Application device 110 is constructed to deliver heat around a deflector128 to either nozzle 130 or nozzle 132. The direction of heat isdistributed by a baffle 134 with a movable wing that impedes the flow ofheated air to either nozzle 130 or nozzle 132. The baffle 134 iscontrolled by a linkage 136 to handle 120 that can pivot forward orbackward along axis X-X. Thus, with minor motion, a person usingapplication device 110 can shift handle 120 to control the direction ofheat reaching the film. That control of direction permits theapplication device 110 to be used in both directions along axis X-Xbecause it is a feature of the invention to heat the film beforeadhering it with pressure to the substrate.

FIG. 3 illustrates application of a film to a substrate using anexemplary application device. Application device 310 has a heat source312 and a pressure source 314 to apply film 330 to surface 340 ofsubstrate 350. Heat source 312 supplies heat to film 330 in the form ofradiation such as infrared rays. In this manner, convection is not usedto transport heat to the film as was used in the embodiments shown inFIGS. 1 and 2.

FIG. 4 illustrates application of a film to a substrate using anexemplary application device. FIG. 4 shows another embodiment to thatseen in FIGS. 1 and 3. Application device 410 has a heat source 412 anda pressure source 414, but heat source 412 directs heat toward a film430 rotating on pressure source 414 before application of the film 430to a surface 440 on a substrate 450. This embodiment demonstrates thatthe location of heating of film can occur on the pressure source as thepressure source is delivering the film to the substrate.

FIG. 5 illustrates application of a film to a substrate using anexemplary application device. FIG. 5 shows an embodiment for a differenttype of surface irregularity or compound surface on an image graphicsubstrate surface: a rivet used to join the surface to a reinforcementon the opposing surface of the substrate. Rivets proliferate on a trucktrailer or delivery van and are very time-consuming to assure filmadhesion thereto. In this embodiment, application device 510 has a heatsource 512 and a pressure source 514, where the pressure source 514 isannular about the heat source 512. The annular pressure source 514 issized to accommodate the raised, compound-curved surface of the rivet.Source 514 can be altered to accommodate any other irregular surfaceshape such as channels, grooves, depressions and other protrusions andindentation. Concentrically within or without the annular pressuresource 514 is the heat source 512, such that the film contacting theraised, compound-curved surface of the rivet or the film surrounding theentire rivet, or both, can be heated concurrently with the applicationof the pressure source 514. Both the heat source 512 and the pressuresource 514 are mounted on a frame 516 that has a handle 518. Frame 516also contains an exhaust port 520 that permits air to escape from theheat source after the annulus of the pressure source 514 has contactedthe surface of the substrate about the rivet.

The materials used for heat source 512, pressure source 514, and frame516 can be the same as the materials used for heat source 112, pressuresource 114, and frame 116 seen in FIG. 2. Optionally, application device510 can also have a temperature sensor 522 and a temperature controllergauge 524 in locations as seen in FIG. 5 for the same purpose asdescribed above with respect to the embodiment seen in FIG. 2.

Because heating and cooling rates of a typical image graphic film areseveral hundred degrees per second, the films very often cool to nearroom temperature before the forming/application can be completed whenthe conventional assembly technique is used. Films applied when the filmis not suitably softened exhibit stress that can cause the adhesive bondto fail. Failure causes the film to lift off the surface, which resultsin poor appearance and film loss. Lifting failures decrease as pressuredapplications are made that approach the melting point of the film beingapplied.

Any of application devices 10, 110, 310, 410 or 510 permit one skilledin the art to apply film at or near its melting point without damagingthe film. The use of a heat source and a pressure source intersectingconcurrently at irregular or compound surface location(s) where film isunder stress unexpectedly minimizes damage to the film. While the filmis hot, it is pressed into position using a roller 14, 114, 314, 414 orannular ring 514 that does not dissipate the heat. When the hot filmcontacts the receptor surface, it is immediately quenched. This processreduces residual stress in the film to a level that can be overcome bymany adhesives, including those that are considered low performance orremovable.

It has been found that an adhesive-coated film, namely Controltac™ 180film, can be successfully adhered using the application devices. The airtemperatures range from about 200° C. to about 400° C., but the actualfilm temperature is best raised to 170 to 200° C. It has also been foundthat use of conventional heat sources that are separated in time andlocation from pressure sources can generate the necessary temperatures,but use of the rivet brush requires the film to cool to approximately100° C., which is insufficient to permanently re-form the film about thesurface irregularity of the substrate.

Controltac™ 180 film, comprising an adhesive disclosed in PCT PatentPublication WO 98/29516, was applied to white painted corrugated metalpanels containing numerous rivets to simulate the outer surface of atruck trailer. The film liner was removed and the film was laid acrossthe tops of the corrugations with light pressure applied to provideinitial adhesion. An application device resembling the illustration seenin FIG. 2 was then rolled down into the valleys between corrugationswhere the pressure source had a soft urethane foam roller while applyingheat at various temperatures. The temperatures were recorded asdisplayed on a Steinel heat gun commercially available from McMasterCarr. The panels with the adhered films were then placed in an agingoven for 6 days and heated to 79° C. The panels were then removed fromthe oven and left untouched for three weeks before measuring the naturallifting of film from around the rivets. The results are seen in Table 1as follows.

TABLE 1 Application Average Lifting Temp (° C.) at Rivets (cm) 65 0.39693 0.277 121 0.317 149 0.317 177 0.256 204 0.119 232 0.119 260 0.109 2880.045

These results show that hot air temperatures above 200° C. for vinylfilms significantly reduces natural lifting of the film around rivets.The film is conformable to the surface irregularity or the compoundcurve of the surface to achieve durable adhesion of the film to thesubstrate.

It has also been found that as much as 80% of the time normally requiredfor adhering a film on a corrugated and riveted substrate can be saved,reducing the total cost of adhering such film by as much as 50%.

What is claimed is:
 1. A method of applying a film having a pressuresensitive adhesive on a major side thereof to a substrate having anirregular surface, the adhesive-applying method comprising: heating aportion of the film to a softening point of the film to form a heatedportion of the film; pressing the heated portion of the film against thesubstrate with an application device, the application device comprisinga film-contacting portion comprising a foam material; and wherein thepressure sensitive adhesive on the major surface of the film associatedwith said pressing adheres to the irregular surface of the substrate ina single pressing.
 2. The method of claim 1, wherein the heatingcomprises heating the portion of the film using hot air.
 3. The methodof claim 1, wherein the heating comprises heating the film usinginfrared radiation.
 4. The method of claim 1, wherein the heating occursbefore pressing the heated portion of the film against the substrate. 5.The method of claim 1, wherein the heating occurs while the portion ofthe film is in contact with the film-contacting portion before pressingthe film against the substrate.
 6. The method of claim 1, whereinheating the portion of the film to the softening point of the filmcomprises heating a selected portion of the film.
 7. The method of claim1, wherein the foam material comprises open cell foam material.
 8. Themethod of claim 8, the open cell foam material comprising cells that areno larger than about 0.5 mm in diameter.
 9. The method of claim 1,wherein the film-contacting portion is in the form of a roller.
 10. Themethod of claim 1, wherein the pressure sensitive adhesive comprises aremovable adhesive.
 11. The method of claim 1, wherein the filmcomprises a vinyl film, polyolefin film, unoriented polyolefin films,polyurethane film, ionomeric resin film, acrylic film, or afluoroelastomeric film.
 12. The method of claim 1, wherein the substratecomprises a highly textured surface.
 13. The method of claim 1, whereinthe substrate comprises a rigid film.
 14. The method of claim 1, whereinthe substrate comprises concrete, cement block, stucco, brick, fabricsurfaces or carpeted surfaces.
 15. The method of claim 1, wherein thefoam material has a thermal conductivity of less than 1.8BTU/hr-in-ft²-° F.
 16. The method of claim 1, further comprising: beforethe heating and pressing steps, tenting the film against the substrate.17. The method of claim 1, wherein the heated portion of the film thathas been pressed against the substrate closely conforms to thesubstrate.
 18. The method of claim 1, further comprising: repeating thepressing step.
 19. The method of claim 1, wherein the film comprises avinyl film, polyolefin film, unoriented polyolefin films, polyurethanefilm, ionomeric resin film, acrylic film, or a fluoroelastomeric film.20. A method comprising: distributing a film comprising pressuresensitive adhesive coated on a major surface thereof, to a party; and,instructing the party to apply the film to a substrate having anirregular surface by performing an application method comprising:heating a portion of the film to a softening point of the film to form aheated portion of the film; pressing the heated portion of the filmagainst the substrate with an application device, the application devicecomprising a foam-based film-contacting portion; and wherein thepressure sensitive adhesive on the major surface of the film associatedwith said pressing adheres to the irregular surface of the substrate ina single pressing.
 21. The method of claim 20, wherein the heatingcomprises heating the portion of the film using hot air.
 22. The methodof claim 20, wherein the heating comprises heating the film usinginfrared radiation.
 23. The method of claim 20, wherein the foam-basedfilm-contacting portion comprises open cell foam material.
 24. Themethod of claim 23, wherein the open cell foam material comprises cellsthat are no larger than about 0.5 mm in diameter.
 25. The method ofclaim 20, wherein the foam-based film-contacting portion is in the formof a roller.
 26. The method of claim 20, wherein the substrate comprisesconcrete, cement block, stucco, brick, fabric surfaces or carpetedsurfaces.
 27. The method of claim 20, wherein the foam-basedfilm-contacting portion has a thermal conductivity of less than 1.8BTU/hr-in-ft2-° F.
 28. The method of claim 20, further comprising:before the heating and pressing steps, tenting the film against thesubstrate.
 29. The method of claim 20, further comprising: repeating thepressing step.
 30. The method of claim 20, wherein the film comprises avinyl film, polyolefin film, unoriented polyolefin films, polyurethanefilm, ionomeric resin film, acrylic film, or a fluoroelastomeric film.